[californiadisasters] Is Another Cool Summer Ahead?

Is another cool summer ahead?

June 1st, 2011, 2:51 pm · posted by Pat Brennan, O.C. Register science, environment editor

Last year's cooler-than-normal summer left surfers and sun-seekers grumbling, and some long-range forecasts suggest we might be in for another one.

But at the moment, the forecasts are all over the map, with cases being made for a mostly normal summer for Southern California as well as warmer than normal.

The broad spread of predictions are driven in part by an unusual southward-dipping jet stream, which brought cooler temperatures to Southern California this winter and spring.

The lack of either an El Niño or La Niña pattern — when tropical Pacific waters are warmer or cooler than normal — also is making long-range guesswork difficult.

One cooler-than-normal prediction comes from Bill Patzert, a climate and ocean expert at the Jet Propulsion Laboratory in Pasadena.

"Here on the West Coast there has been unusually cool water off the coast," Patzert said. "That would tend to give us a cooler summer as well. A cool summer just means more marine layer, and all that cold water off the coast is not going to go away. We had the same thing last year."

The southward-dipping jet stream has allowed Arctic air to flow farther south than normal, he said, bringing heavy winter snows to the lower 48 and helping drive recent tornadoes in the midwest, and recent cooler weather on the West Coast.

And the Arctic air, Patzert said, was what confounded another of his predictions: a dry rainy season this year. While the expected La Niña pattern did persist for awhile in the equatorial Pacific, it was overwhelmed by the Arctic pattern, he said, giving us more rain than average.

A mid-range prediction comes from Tom Rolinski, a meteorologist at the Predictive Services unit of the U.S. Forest Service.

His job is to forecast wildfire activity, and his agency's latest outlook calls for a normal fire season for Southern California. That means several large wildfires — those over 300 acres.

Rolinski says coastal Southern California, including Orange County, could see a cool start to summer that warms up into the normal range later.

"We still have a fairly active jet stream across the Pacific and that's still bringing us these (low pressure) systems," he said. "It's not really going to bring us any rain, but just keeping us cooler than normal, and keeping the onshore flow a little stronger."

That pattern could linger through much of June, he said, before warm weather sets in.

"Overall it will not be as cool as it was last summer," he said. And despite an initial delay, that will likely lead to a more active fire season.

"We've got a lot of fuel out there," he said. "The grasses are basically all cured. So once we start getting some heat, we'll start seeing quite a bit of fire activity."

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View entire article here: http://sciencedude.ocregister.com/2011/06/01/is-another-cool-summer-ahead/129123/

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